X-ray filter



Dec. 15, 1925 Y F. TICHY ET AL X-RAY FILTER Filed Oct. 31. 1923 VENTOR l iii/var THE/ RA'ITORNEX Patented Dec. 15, 1925.

UNITED STATES PATENT OFFICE.

FREDERICK TICHY, OE ASTORIA, AND ARTHUR CHARLES KOEN'ITZ, OF NEW YORK, N. Y., ASSIGNORS TO WAPPLER ELECTRIC COMPANY, INC., A CORPORATION OF NEW YORK.

X-RAY FILTER.

Application filed October 31, 1923. Serial No. 671,842.

To all whom it may concern:

Be it known that we, FREDERICK TIo H Y and ARTHUR C. KOENITZ, both being citizens of the UnitedStates, the former re- 6 sidin in Astoria, in the county of Queens and i tate of New York, and the latter residing in New York, in the county and State of New York, have invented certain new and useful Improvements in X-Ray Filters, of which the following is a full,

clear, and concise description.

Our invention relates to X-ray filters; that is, to devices used in connection with X-ray tubes for the purpose of intercepting and thereby destroying secondary or scattering X-rays.

More particularly stated, our invention comprehends an X-ray filter in the form of a grid to be used in connection with the X-ray tube, and which while in action may be either movable or stationary, depending upon the character of the work and the roportions of the filter, our invention being concerned more especially Wlth the construction of the filter.

X-ray filters of the general type here contemplated have sometimes been made in the form of a grid, consisting partly of hard material such as wood or celluloid easily 3o permeable to X-rays, and partly of th n and narrow strips of metal of high atomic weight, these strips being relatively impervious to the X-rays. In some instances the filter thus has had the form of a board,

which was either fiat, curved spherically or curved cylindrically, as the case may be.

As a general rule, however, the filters constructed in the manner just mentioned have been complicated and expensive, orv else un- 4 satisfactory for other reasons.

What we seek to do, therefore, is to provide a filter of such form, construction and arrangement as to facilitate its ease of manufacture and yet to maintain a high degree of efficiency. I i

We also seek to produce a filter which can be rendered very thin and compact, and which is especially adapted for fluoroscopic examinations. In addition, we seek'to give the filter such construction as not to obstruct fluoroscopic vision whether the filter, while in action, be fixed or movable in position.

Broadly speaking, our invention relates to the manner of mounting a number of thin and narrow grid bars upon a suitable board, in order to produce a filter having the advantages We claim.

Reference is made to the accompanying drawing forming a part of the specification and inwhich like reference characters indicate like parts throughout the several figures.

Figure 1 is an elevation showing one form of our improved filter, and an X-ray tube as used therewith.

Figure 2 is an enlarged fragmentary elevation of a filter similar to the one appearing in Figure 1.

Figure 3 is an enlarged fragmentary elevation showing another form of our improved filter.

Figure 4: is a fragmentary perspective showing a spacing bar and a pair of metallic strips mounted thereupon, as used in the form of my improved filter appearing in Figures 1 and 2.

Figure 5 is a fragmentary perspective of a pair of spacing bars and the metallic strips carried thereupon, as used in the form of my grid appearing in Figure 3.

An X-ray tube appears at 6 and may be of the usual or any desired construction. This X-ray tube is provided with a target 7, from which the primary X-rays are thrown off. From the target the X-rays emanate in straight lines, as indicated by the broken lines 8 and 9.

In the form of my filter appearing in Figures 1 and 2 we provide a thin, fiat, wooden board, into one face of which are cut slots 11, these slots being inclined to different angles as indicated in Figures 1 and 2, and so formed that with the board in position relatively to the X-ray tube and ready for use, as indicated in Figure 1, the several slots each extend edgewise toward the target 7, or in other Words toward the ,focal spot from which the primary rays reach the board from the X-ray tube.

A number of spacing bars 12, each made of wood, are each provided With a pair of strips 13, made of lead or other metal of high atomic weight and thus as far as practicable impermeable to X-rays.

The strips 13 are secured firmly upon the spacing bar 12 by means of an adhesive such as glue or paste, and each spacing bar, with its strips thus adhering to it, is forced edgewise into some one of the slots.

By this arrangement the metallic strips 13 are each at all times kept spread out flat throughout its entire length and width, and free from wrinkles. A spacing bar, thus provided with metallic strips as just described and as shown in Figure 4, holds its two metallic strips properly spaced apart, no matter whether the spacing bar be fitted into the position upon the board or not.

In order to provide the board 10 with the slots 11 and to give these slots the proper inclination, as indicated in Figures 1 and 2, the board is preferably forced endwise beneath a gang of circular saws or milling cutters, inclined radially toward each other. Or, if desired, the board may be cut by the repeated action of a single saw, either the saw or the board being adjusted into a new position after cutting one slot and before cutting the next.

When the various spacing bars, each with its pair of metallic strips, are severally forced into position as above described, the board has the appearance indicated in Fig ures 1 and 2. Each strip 11 now extends edgewise substantially in the direction of the focal spot of the target.

In some instances, and particularly when it is desired to produce a grid of relatively fine texture, we employ the construction shown in Figures 8- and 5.

The board 14 is provided with slots 15,

these slots being rather wide, and so positioned that they severally extend edgewise toward a particular spot. Spacing bars 16, made of wood and. formed into pairs, are provided with strips 17 of lead or other appropriate metal, arranged as shown in Figure 5, the structure thus built up constituting a double spacing bar. The several double spacing bars are forced edgewise into the slots 15, as indicated in Figure 3.

With the grid thus constructed the various slots 17 severally extend edgewise in the proximate direction of a single point.

With the form of my device shown in Figures 1 and 2 the slots may be one-eighth of an inch in width, each spacing bar with its pair of metallic strips being also of that width.

lVith the form shown in Figure 3 each slot may be less than a quarter of an inch in width, the double spacing bar with its three metallic strips being of proper thickness fit into the slot.

In all forms of our grid the spacing bar with its accompanying parts should fit rather tightly in position.

While as a general rule it is preferable to make and sell each grid as a complete article of manufacture, this is not strictly necessary. The boards, each provided with slots, may be manufactured and sold independently of the spacing bars and strips; and the spacing bars, with or without the strips attached thereto, may be manufactured and sold as spacing bars, independently of the board.

In the event that any one or more of the spacing bars become damaged, the same may be removed and replaced by others. If a particular board becomes damaged or worn out, any spacing bars and metallic strips carried by it, if in good condition, may be removed from it and placed in some other board.

lrlthough as above indicated certain dimensions for the slots and spacing bars may be employed, the particular dimensions mentioned are chosen arbitrarily, manifestly the dimensions may be varied within reasonable limits. As a general rule, if the grid is to be stationary while in use the slots should be relatively narrow and the spacing bars correspondingly thin. If, however, the grid is to be in motion while the rays are passing through it, larger dimensions may be found advantageous.

The operation of our improved filter is in general like that of other X-ray filters heretofore employed. The primary X-rays, proceeding radially outward in straight lines from the focal spot of the body, pass practically unimpeded through the slots. The secondary rays, however, being generated by action ofthe primary rays upon various objects in the vicinity of the X-ray tube, are intercepted to a greater or lesser extent, simply because they do not as a rule travel in the right direction to pass freely between the strips. Thus the work of the filter is to intercept the secondary X-rays to a greater extent than it does the primary X-rays.

We do not limit ourselves to the particular mechanism shown and described, as variations may be made therein without departing from our invention, the scope of which is commensurate with our claims.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is as follows:

1. As an article of manufacture, an X-ray filter having the general form of a grid and comprising a board provided with slots, and a number of spacing bars and metallic strips fitted into said slots.

2. An X-ray filter comprising a board made of material easily permeable to X-rays, said board being provided with a plurality of slots, and a number of spacing bars fitting into said slots, said spacing bars being provided with metallic strips adhering thereto, the number of metallic strips being greater than the number of said spacing bars.

3. As an article of manufacture an X-ray filter comprising a board provided with slots and made of material easily permeable by X-rays, a plurality of spacing bars made of opaque to X-rays, said spacing bars and strips occupying said slots.

4. As an article of manufacture an X-ray filter comprising a board provided with slots extending into it but not entirely through it, and a plurality of spacing bars and metallic strips occupying sald slots and thus carried by the board, said board and said spacing bars bein made of material easily permeable by -rays.

5. As an article of manufacture a filter of the character described, comprising a board provided with slots and being flat from edge 15 to edge, said board being made of material easily permeable by X-rays, and said slots being each of the same width at different depths within the board, and a plurality of wooden spacing bars and metallic strips 20 occupying said slots, each spacing bar being located between two of said metallic strips immediately adjacent thereto.

FREDERICK TICHY. ARTHUR CHARLES KOENITZ. 

